/********************************************************************************
  * @file    codeeditor.cpp
  * @author  Lun Li
  * @version V2.2.0
  * @date    2022.7.8
  * @brief   This file provides all CodeEditor functions.
  *******************************************************************************/

#include "codeeditor.h"

#include <QMimeData>
#include <QPainter>
#include <QTextBlock>

CodeEditor::CodeEditor(ProgramConfig *const config, Source *file, QMenu *menu, QWidget *parent)
    : QPlainTextEdit(parent),
      contextMenu(menu),
      m_file(file),
      m_config(config)
{
    //初始化行号区域与语法高亮器
    lineNumberArea = new LineNumberArea(this);    
    new VerilogSyntaxHighlighter(config, document());

    // 连接信号槽
    connect(this, &CodeEditor::blockCountChanged, this, &CodeEditor::updateLineNumberAreaWidth);
    connect(this, &CodeEditor::updateRequest, this, &CodeEditor::updateLineNumberArea);
    connect(this, &CodeEditor::cursorPositionChanged, this, &CodeEditor::highlightCurrentLine);    
    connect(m_config, &ProgramConfig::editorConfigChanged, this, &CodeEditor::updateEditorConfig);

    setLineWrapMode(NoWrap);
    updateLineNumberAreaWidth(0);
    highlightCurrentLine();    
    updateEditorConfig();

}

CodeEditor::~CodeEditor()
{
    // 若该文件不在工程中，则关闭编辑器时就删除文件指针
    if (!m_file->projectItem()) {
        m_file->deleteLater();
        m_file = nullptr;
    }
}

int CodeEditor::lineNumberAreaWidth()
{
    // 计算行数的位数
    int digits = 1;
    int max = qMax(1, blockCount());
    while (max >= 10) {
        max /= 10;
        ++digits;
    }

    // 根据行号的位数计算宽度
    int space = 3 + fontMetrics().horizontalAdvance(QLatin1Char('9')) * digits;

    return space;
}

void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
    setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}

void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
    if (dy) { // 行号随文本一起滚动
        lineNumberArea->scroll(0, dy);
    } else { // 更新行号区域
        lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());
    }

    if (rect.contains(viewport()->rect())) {
        updateLineNumberAreaWidth(0);
    }
}

void CodeEditor::updateEditorConfig()
{
    setFont(m_config->font());
    setTabStopDistance(m_config->tabWidth() * QFontMetrics(m_config->font()).horizontalAdvance(" "));
}

Source *CodeEditor::file() const
{
    return m_file;
}

void CodeEditor::resizeEvent(QResizeEvent *e)
{
    QPlainTextEdit::resizeEvent(e);

    QRect cr = contentsRect();
    lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}

void CodeEditor::focusInEvent(QFocusEvent *e)
{
    QPlainTextEdit::focusInEvent(e);
    emit focusChanged(true);
}

void CodeEditor::focusOutEvent(QFocusEvent *e)
{
    if (e->reason() != Qt::FocusReason::PopupFocusReason) {
        QPlainTextEdit::focusOutEvent(e);
        emit focusChanged(false);
    } else {
        e->ignore(); // 点菜单则不失去焦点
    }
}

void CodeEditor::contextMenuEvent(QContextMenuEvent *e)
{
    // 弹出菜单
    contextMenu->exec(e->globalPos());
}

void CodeEditor::highlightCurrentLine()
{
    QList<QTextEdit::ExtraSelection> extraSelections;

    if (!isReadOnly()) {
        QTextEdit::ExtraSelection selection;

        QColor lineColor = QColor(Qt::yellow).lighter(160);

        selection.format.setBackground(lineColor);
        selection.format.setProperty(QTextFormat::FullWidthSelection, true);
        selection.cursor = textCursor();
        selection.cursor.clearSelection();
        extraSelections.append(selection);
    }

    setExtraSelections(extraSelections);
}

void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
    QPainter painter(lineNumberArea);
    painter.fillRect(event->rect(), Qt::lightGray);

    QTextBlock block = firstVisibleBlock();
    int blockNumber = block.blockNumber();
    int top = qRound(blockBoundingGeometry(block).translated(contentOffset()).top());
    int bottom = top + qRound(blockBoundingRect(block).height());

    while (block.isValid() && top <= event->rect().bottom()) {
        if (block.isVisible() && bottom >= event->rect().top()) {
            QString number = QString::number(blockNumber + 1);
            painter.setPen(Qt::black);
            painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
                             Qt::AlignRight, number);
        }

        block = block.next();
        top = bottom;
        bottom = top + qRound(blockBoundingRect(block).height());
        ++blockNumber;
    }
}



